This invention relates to copy sheet discharge apparatus for use in electrophotographic appliances such as laser beam printers or copying machines (thereinafter referred to as copying machines) wherein immediate checkup of the image-bearing faces of copy sheets is made when the copy sheets are either under delivery to a copy holding tray or in stacked position in the copy sheet holding tray in the proper sequence of the original documents.
Two types of copying machines have been provided according to copy sheet discharging methods; one face-up type as shown in FIG. 1A and the other, face-down type as shown in FIG. 1B.
In the prior art face-up type copying machine as shown in FIG. 1A, the image on an original document on the document table is scanned by a scanning unit that includes exposure lamp and reflection mirror (not shown) and the scanned image beam is irradiated on the outer periphery of a photosensitive drum 3 through lens 1 and reflection mirror 2.
The photosensitive drum 3 has been charged with a predetermined potential by a charging means 4 before the image beam is irradiated thereon, thus forming an electrostatic latent image corresponding to the original document when irradiated by the image beam. The toner having been mixed with a developer in a developer reservoir 5 is applied to the electrostatic latent image, while copy sheets in a copy sheet holding cassette (not shown) are fed between the photosensitive drum 3 and a transfer means 6 through a sheet feed path 7.
The transfer means 6 then transfers the toner on the photosensitive drum 7 to the copy sheets.
The toner-transferred copy sheets are successively fed to and heated by a fusing roller set 8 comprising a heating roller 8A and a pressure roller 8B, and fused to the copy sheets. The toner remaining on the surface of the photosensitive drum 3 is removed by a cleaner 9. The copy sheets through the fusing roller set 8 are advanced by a feed roller set 10A and 10B and stacked into piles in a copy sheet holding tray 13 one over another. The copy sheet holding tray 13 is mounted adjacent to one side of upper and lower cover members 11 and 12.
This face-up type has the advantage of immediate checkup on the degree of copy that can be made when the copy sheets are either being delivered to a copy holding tray or stacked into piles in the copy holding tray. However, the disadvantage is that the stack of copy sheets has to be rearranged because the copy sheets are stacked in the reversed sequence of the original documents.
On the other hand, in the face-down type copying machine as shown in FIG. 1B, the copy sheet holding tray 13 is provided on the upper cover 11, and the copy sheets are fed to and stacked into piles in the copy sheet holding tray 13, with the image-bearing faces facing downwards. This face-down type copying machine has the advantage that the rearrangement of the stack of copy sheets is not required because the sheets are stacked in the same sequence as the original documents. However, the disadvantage is that the degree of copy cannot be checked up during the delivery of copy sheets to the copy holding tray. Therefore, after the copy process has been completed, it would be time-consuming to recopy the documents.